My take on some historical religious/social/political movements:

• Jesus taught a radical and highly impractical doctrine of love and disregard for one's own welfare. Paul took control of much of the church that Jesus' charisma had built, and reworked this into something that could function in a real community, re-emphasizing the social mores and connections that Jesus had spent so much effort denigrating, and converting Jesus' emphasis on radical social action into an emphasis on theology and salvation.
• Marx taught a radical and highly impractical theory of how workers could take over the means of production and create a state-free Utopia. Lenin and Stalin took control of the organizations built around those theories, and reworked them into a strong, centrally-controlled state.
• Che Guevara (I'm ignorant here and relying on Wikipedia; forgive me) joined Castro's rebel group early on, rose to the position of second in command, was largely responsible for the military success of the revolution, and had great motivating influence due to his charisma and his unyielding, idealistic, impractical ideas. It turned out his idealism prevented him from effectively running government institutions, so he had to go looking for other revolutions to fight in while Castro ran Cuba.

The best strategy for complex social movements is not honest rationality, because rational, practical approaches don't generate enthusiasm. A radical social movement needs one charismatic radical who enunciates appealing, impractical ideas, and another figure who can appropriate all of the energy and devotion generated by the first figure's idealism, yet not be held to their impractical ideals. It's a two-step process that is almost necessary, to protect the pretty ideals that generate popular enthusiasm from the grit and grease of institution and government. Someone needs to do a bait-and-switch. Either the original vision must be appropriated and bent to a different purpose by someone practical, or the original visionary must be dishonest or self-deceiving.